Unmanned submersible vehicle with on-board generating capability

ABSTRACT

An unmanned submersible vehicle which has the capability to be remotely operated is powered by on on-board battery. The battery is recharged while the vehicle is operating by a turbine driven by the flow of water past the vehicle. The vehicle may also be coupled to a base station by a cable for control purposes. The cable is spooled on a cable spool mounted in or on the vehicle, so the vehicle unspools the control cable as the vehicle moves away from the base station.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to provisional application No.60/670,375 entitled “UNMANNED SUBMERSIBLE VEHICLE WITH ON-BOARDGENERATING CAPABILITY”, filed Apr. 11, 2005.

FIELD OF INVENTION

This invention relates generally to unmanned submersible vehicles, andspecifically to such vehicles for inspection and/or repair of structuressuch as pipes, tunnels, or aqueducts from a location internal to thestructure.

BACKGROUND

Unmanned submersible vehicles are well known. These submersible vehiclesare remotely or autonomously operated. The remotely operated vehiclesare linked to a head end or base via a cable carrying signals to andfrom the base and in some cases carrying electric power from the base tothe vehicle. Such vehicles have a number of uses, for instanceinspecting underwater structures, exploring the bottom of the ocean,etc. One particular use is inspecting the interior of large diameterpipe structures such as water conduits. Also such vehicles are used forrepair of such structures. Typically, such structures are aqueducts,tunnels, shafts, outfalls, conduits and other fluid carrying structureswhere internal access is difficult. Accessing such structures requirelong horizontal excursions from the access points. It is desirable toperform inspection and/or repair under submerged conditions, that iswhen the structure is carrying water rather than attempting to dewaterthe structure. In many cases, such structures cannot have theiroperation interrupted in order to dewater them, for instance when theyare carrying water supplies to a municipality. In some cases dewateringof the structure may cause damage.

Existing remotely operated vehicles have been developed to provide forsubmerged horizontal penetrations up to e.g. six miles long. Theseremotely operated vehicles are controlled via an umbilical cable andprovide real time information from the vehicle back to the base throughthe umbilical. Autonomous underwater vehicles on the other hand areuntethered (no cable) and capable of long distance horizontal/verticalexcursions. However, it is often difficult to maintain real-timecommunication to the base through the body of water or other fluidparticularly if the submerged system is a tunnel or aqueduct. The use ofautonomous vehicles is not indicated for use in this situation with thepresently existing capabilities of through water data transmission ifreal-time information transfer is required over significant submergedtunnel distances.

The typical remotely operated submersible vehicle is powered andcontrolled through the umbilical cable pulled behind the vehicle. Even aneutrally buoyant cable creates considerable drag which must be overcomeby the forward thrust of the vehicle. Waterflow within for instance anaqueduct (tunnel or conduit) in which the vehicle is traveling and/orany bends in the aqueduct which allow the tether to contact a tunnelwall further increase the cable drag. Long tunnel penetrations require avery lengthy umbilical cable, for instance miles long. Further, theumbilical must include an electrical conductor if it is to carryelectric current to the vehicle for powering same. The size and weightof the conductor can be increased for a long umbilical, or the electricvoltage can be increased to transmit power through the umbilical.However, each of these options creases problems for the vehicle. Forinstance, conductor weight can be offset by umbilical floatation.However, that increases the umbilical diameter, surface area and drag.Increasing the voltage of the supplied electric power creates problemswith insulation, heat, and durability of the umbilical. Hence in generalthe horizontal capability (travel distance) of such remotely operatedvehicles is limited by the umbilical cable and its handling systems.

SUMMARY

This disclosure is directed to an unmanned submersible vehicle whichincludes features to provide extended horizontal penetrationcapabilities, control and data transmission and enhanced operationalflexibility, for instance, within submerged conduits such as aqueducts.

Most conventional remotely operated vehicles operate by towing a cablebehind them, which supplies the power and also two-way datatransmission. As pointed out above, in spite of the use of neutralbuoyancy cables, there is an increase in drag dependent upon the surfacearea of the cable, water flow conditions, and contact with the interiortunnel or conduit surfaces. In accordance with this disclosure, aremotely operated vehicle carries, in addition to a conventional onboardelectrical power source such as rechargeable batteries, the capabilityto recharge those batteries by an onboard generator which is operated bywater flow within the tunnel (conduit, etc.). This has severaladvantages, since as a result the cable itself can be very thin since itonly need carry data signals rather than electrical power. Typicallythis is a fiber optic cable including also strengthening members andabrasion protection as well known in the field. There may be a verysmall diameter electrical conductor in the cable to trickle charge thevehicle's onboard rechargeable batteries. In other cases, the conductormay be entirely omitted from the cable. Since the cable is relativelythin and light, long lengths of same can be easily pulled by the remoteoperated vehicle as necessary. Alternatively, it is possible to storelong lengths of the relatively light and thin cable onboard the vehicleinstead of dragging it behind. In this case, the onboard length of cableis typically on a spool and the cable is unspooled as the vehicletravels down the conduit away from the base. If desireable, it can besubsequently respooled as the vehicle returns to its base.Alternatively, the cable can be retrieved and extracted from the conduitseparately.

This configuration allows water flow through the conduit to bemaintained while the submersible travels through same. For the generatorto operate, the vehicle can be temporarily fixed in a stationaryposition or slowed within the conduit. This is accomplished inaccordance with this disclosure by providing a locking mechanism such asa strut extending from the vehicle which pins the vehicle on the conduitwall. In this case the vehicle itself may have negative buoyancy and soride along the bottom of the conduit, or have neutral or positivebuoyancy. Hence the extended strut extends to a far wall of the interiorof the conduit fixing the vehicle in place on the wall while the turbineoperates to recharge the battery. During this time, there is no need toalter normal water flow through the conduit. Advantageously with thisconfiguration, inspection and repair work using the vehicle within theconduit is not limited to times when the tunnel is not carrying water.Of course this is a major advantage since in many cases shutting downthe water flow in the conduit for other than short periods isundesirable. Moreover, the locking mechanism can position the vehicle ina particular position for inspection purposes while normal water flow isresumed. This allows observance of faults in the conduit such as cracksduring conditions of normal tunnel flow, which is often useful.

The present vehicle thus has a relatively long range so that it canoperate far away from its base, as determined by the length of onboardcable. This allows simplified operation since there is no need forfrequent introduction and removals of the vehicle to the conduit. Ofcourse, for many conduits the access points are widely spaced apart andit is not possible to operate a vehicle having a short range within suchconduits.

The cable which in accordance with this disclosure is unspooled from thevehicle rather than being dragged behind creates advantages for tunneland conduit penetration. Such a cable which is unspooled rather thandragged is less susceptible to fouling on internal obstacles. Also sinceit is not laid under tension, retrieval of the cable when it is fouledis easier than if it is jammed in place on an obstacle when dragged asin the prior art. Additionally, such a cable that is unspooled ratherthan dragged behind the vehicle need not be neutrally buoyant butinstead may be negatively buoyant and hence lay along the conduit floor.Further, such contact with the floor of the conduit by the cabletypically reduces friction on the cable during intervals of water flowwithin the conduit. The vehicle can exit the conduit by progressing backalong its path and respooling the cable previously laid out. Typicallythe cable is spooled upon a cable spool in the vehicle which is drivenby an electric motor also within the vehicle for unspooling andrespooling purposes. A conventional spool cable brake may also beprovided.

Further considered in accordance with this disclosure is the possibilityof vehicle operational failure. For instance, if the vehicle cannotretreat and respool its cable for reasons such as a fouled cable, thevehicle has the capability using an onboard guillotine (severingmechanism) to sever the cable. This condition may be determined by anonboard controller/microprocessor. The severing may also be commandedfrom the base if the vehicle is still in contact with the base via thecable. In any case, upon loss of base contact or severing of the cable,the vehicle automatically reverts to a preprogrammed autonomousunderwater vehicle mode and then proceeds to exit the conduit under itsown control. The damaged or severed cable may be removed separately. Inthis case, additionally if for some reason if the vehicle cannot exitthe conduit in the normal autonomous underwater vehicle mode, it may beprogrammed to deploy a drogue which will remove it from the conduitunder the force of normal conduit water flow. This is important sinceone cannot leave a disabled vehicle in the conduit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B and 1C show overall views of a submersible in accordancewith this disclosure;

FIG. 2 shows a detailed view of the turbine portion of the on-boardelectric power generator in accordance with this disclosure;

FIGS. 3A and 3B show detailed views of the on-board cable spool andassociated mechanisms in accordance with this disclosure;

FIG. 4 shows a detailed view of the extendible strut (prop) inaccordance with this disclosure.

FIGS. 5A and 5B show detailed views of a guillotine mechanism forsevering the cable in accordance with this disclosure.

DETAILED DESCRIPTION

FIG. 1A shows an overall partially cut away view of relevant features ofa submersible 12 in accordance with this disclosure. This is likely aremotely operated vehicle but may be in another embodiment or aspects ofits operation an autonomous underwater vehicle. Only relevant featuresare shown here. Conventional features including the rechargeablebattery, pumps, valves, electric motors, inspection apparatus (forinstance illumination and video cameras), signal processing circuitryetc., are not shown for simplicity. This particular submersible isintended primarily for use in closed spaces such as aqueducts, conduits,pipes, etc. The depicted version crawls along the interior bottom of apipe or conduit. However, in other embodiments it is not so limited. Thevehicle size is a matter of design choice depending on the diameter ofthe particular conduit/pipe in which the vehicle is to be used.Typically the vehicle is significantly smaller in diameter than the pipein which it is intended to operate. Actual inspection typically takesplace through the vehicle's housing or with ancillary systems such asvideo cameras, sensors, etc. In other embodiments, the submersiblevehicle is also provided with apparatus for repair of flaws or faults inthe conduit.

In any case, in FIG. 1A, submersible vehicle 12 includes a chassis orplatform 14 to which is mounted a housing 16 which is typically sealedso as not to admit water therein. Mounted on the chassis 14 are twobuoyancy (air/water) tanks 18 a, 18 b for controlling buoyancy of thevehicle, as is conventional together with associated conventional pumps,valves, compressed air supply, etc. (not shown). In one embodiment thissubmersible has negative buoyancy but the buoyancy may be adjustable.The submersible moves on a set of tracks; in this case, rear tracks 20 aand 20 b and a single front track 22 a are visible with the other fronttrack being hidden. These tracks are conventionally driven by motorinside the housing 16 which is electrically coupled to a rechargeablebattery. There may be independent motors provided for each track ortrack pair or there may be a gearing mechanism linking an electric motorto various of the tracks. The tracks also allow steerability. Instead oftracks there may be in another embodiment wheels and/or articulatedlegs. The tracks are conventionally driven by bogies and the tracksthemselves are e.g. steel and/or rubber or plastic.

For control purposes, at the rear of the submersible 12 is port 28 fromwhich emerges the cable 30 which typically carries control signals toand from the submersible 12. Typically this is a fiber optic cable withstrength members and an outer coating for protection purposes. Cable 30may also include an electrical conductor as discussed above, but notnecessarily. If there is an electrical conductor, it may be ofrelatively smaller diameter so the cable is relatively thin, flexibleand light. At the front of submersible 12 is a pair of manipulatordevices of which only the left most 32 a is visible. There is a similarmanipulator device on the front right side of submersible 12, notvisible here, and additional general purpose and/or special purposemanipulators and/or work devices can be mounted elsewhere upon platform14.

Extending outward from the housing 16 are two struts or props or jacks36 a, 36 b each terminating in a prop extension 40 a, 40 b. As shown,extensions 40 a, 40 b are curved so as to fit snugly against theinterior wall of the conduit. (Typically the interior of the conduit iscurved.) Extensions 40 a, 40 b may include somewhat soft material suchas plastic and/or rubber to avoid damaging the interior wall of theconduit. The telescoping props 36 a, 36 b are rigid and thereby theextensions 40 a, 40 b fit snugly against the interior of the pipe whenthe submersible 12 is to be stationary. Hence, when it is intended tomake the submersible stationary, tracks 20 a, 20 b, etc. rest againstthe bottom wall of the pipe interior and the props 36 a, 36 b with theirextensions 40 a and 40 b pin the submersible 12 in a particular positionin spite of the water flows through the conduit. The struts depicted arebut one possible embodiment of a jacking system deployed to fix thevehicle in stationary position within the tunnel. It is to beappreciated that submersible 12 is typically used when the conduit iscarrying water at a relatively large rate of flow. Of course, this isnot necessarily the case and the submersible 12 will also work in a dryaqueduct or pipe or conduit.

Submersible 12 makes use of the potential energy of the water travelingunder pressure in the tunnel, pipe, conduit, aqueduct, etc., and thesubmersible is arranged so that it generates electric power from thewater flow whenever the velocity of water (or other fluid) in theconduit differs from that of the speed of the vehicle. Hence, there areprovided extending outside the housing 16 turbine devices 44 a, 44 b,mounted respectively on supports 46 a, 46 b. In this case, the turbines44 a, 44 b extend well out of the housing. In other embodiments, theymay be built wholly or partially into the housing and connected to theexterior through flow channels. Each turbine includes an impeller,further detail of which is described below. The impeller rotates whenthe speed of the vehicle through the conduit differs from that of thewater flow therethrough. Hence the water flow will spin each impellerwhich may be connected mechanically through its support 46 a, 46 b to agenerator which generates electricity thereby and the electricity thenis typically coupled into the rechargeable battery (not shown, butconventional) present in housing 16. In other cases, each impeller hasan integrated generator to generate electricity which then is coupled tothe rechargeable battery through electrical conductors extending throughsupports 46 a, 46 b. Such small turbine/generator combinations are wellknown in the electrical engineering field. In other embodiments of thisvehicle, the turbines may be powered and used as thrusters to maneuverthe submerged vehicle.

The self-charging/re-charging design of this vehicle is obviously notlimited to tunnels or conduits. The use of differential water flowvelocities for power generation is equally applicable to prevailingcurrent situations, tidal bores, and/or other situations involving watermovement.

The use of propulsive-thruster motors as part of a non-tracked neutrallybuoyant underwater vehicle will allow the machine to be propelledthrough the water in the “thruster mode” or alternatively recharge thevehicle in the “generator mode”. Large diameter low-pitch propellers maybe used for vehicle locomotion then the propeller pitch can be remotelyaltered to become a low-speed high-pitch electrical generator.Appropriate solid state permanent magnet motor-generators are readilyavailable technology.

The other structure of interest in FIG. 1A is the cable spool 50,further details of which are given below, on which is wound a length ofthe cable 30 inside the housing 16. As described above, submersible 12need not necessarily obtain its electric power through the cable whichthereby can be relatively thin and light. Moreover, of course, since thesubmersible unspools and spools its cable 30 it need not drag a longlength of cable.

Hence, in accordance with this disclosure the submersible has theability to stop its progress through the conduit and remain stationarywithin the conduit. The water flowing around the submersible spins theimpellers in turbines 44 a, 44 b to generate electrical current torecharge the battery. In other embodiments the submersible may carrydevices to slow its progress relative to the flowing water. In thatcase, the struts 36 a, 36 b need not be deployed in order to stop thevehicle in the conduit.

Charging the batteries may take place continuously or at intervals.Typical slowing devices could be several long, highly flexible membersthat attach to the submersible and trail behind it and make contact withthe conduit walls. Such springy “whips” or flexible members may beaffixed to the housing 16 so that they are angled off the horizontal,and can be controlled and adjusted remotely, that is, from the controlbase. This ability allows the bearing force against the walls of theconduit to be increased or decreased and thereby alter the speed of thesubmersible relative to the water flow. Also, in the case of a trackedsubmersible which travels on the bottom, or even the top of the conduit,the weight or balancing of such a submersible may be remotely controlledby allowing water to enter or be pumped out of the tanks 18 a, 18 b toachieve optimal flow differential speed in order to control both thespeed of travel and the amount of electrical charging continuously.

Note that the particular configuration shown in FIG. 1A is not limiting.For instance, while two props 36 a, 36 b are shown there may be one orthree or other numbers. Similarly, while two turbines 44 a, 44 b areshown there may be one or more, depending on electrical generatingneeds. Also the size of these turbines may be altered.

Since the FIG. 1A submersible is typically for use in an aqueductcarrying water which has already been at least partly filtered, there isno concern in this particular embodiment about particles or debrisjamming the turbines. However, if the submersible is to be used in aless benign environment, then filters/screening devices may be providedto protect the impellers in the turbines from being clogged by debris.These filters would be located on the intake side of each turbinehousing. Similarly, the actual configuration of the impellers isdependent upon the relative speed of the submersible during powergeneration phase and hence is a design consideration.

The FIG. 1A submersible is shown in a rear view in FIG. 1B with the samestructures identified with the same reference numbers. Additionallyshown in this view is axle 52 which carries tracks 20 a, 20 b.

FIG. 1C shows a side partial cut away view of submersible 12 with thesame structures identified with the same reference numbers. In this casethe cable spool 50 is better shown, including its traveler 54 for layingthe cable on the spool 50. Traveler 54 moves back and forth onhorizontal tracks 74 as it is conventional with cable spools. Alsoprovided is a cable brake not shown, but conventional. The cable spoolitself is rotated by a drive motor in either the forward or reversedirection to unspool and spool cable. This motor is conventional and notshown. The cable spool drive motor is coupled to cable spool 50 by amechanical linkage or may be a direct drive. This motor is also poweredeither directly or indirectly by the rechargeable battery in housing 16.

FIG. 2 shows detail of one of the turbines 44 a on its telescoping prop46 a. The telescoping is under control of an electric motor orhydraulics located within housing 16 and not shown. At certain timesduring operation of the submersible, for instance, when it is introducedor removed from the pipe, it would be desirable to collapse the props sothat the turbine portion 44 a is as close as possible to the housing sothat it is unlikely to foul. In this case, as shown the turbine 44 a iscoupled by its extensible prop 46 a to a base 62 which is mounted to thehousing 16 or chassis 14. The turbine 44 a includes outer portion 64inside of which is mounted a hub 60, which carries the actual impellerblades 66. As stated above, in some embodiments, hub 60 includes theactual electric generator driven by the rotation of the impeller 66, andthe generator in hub 60 is coupled by an electrical connection throughstrut 46 a to the battery for recharging purposes. Of course,conventional circuitry for power processing in terms of current andvoltage regulators, etc., may be provided to protect the battery.

To give an idea of scale in one embodiment, each impeller is about 20inches in diameter (50 cm). The size is dependent upon the use and powerneeds of the submersible. FIG. 3A shows an enlarged partial view ofsubmersible 12 showing chiefly the cable spool apparatus with the samereference numbers as in the prior figures. The cable spool 50 has endpieces 70 a, 70 b. End pieces 70 a, 70 b accommodate the cable of whichin this case only a single strand 30 is shown. It is to be understoodthat typically the cable spool carries multiple layers of spooled cable30 extending from end piece 70 a to end piece 70 b. Traveler 54 travelsback and forth, horizontally, on the horizontal members 74 to locate orremove the cable from the spool. Such arrangements are well known in thefield. Traveler 54 may include an idler 55. Cable 30 also passes overidlers 57 and 59. The right hand end piece 70 b is driven by an electricmotor and/or gear or belt linkage not shown to rotate the cable spool.The cable spool rotates in either direction for spooling and unspoolingthe cable consonant with movement of the submersible 12. Also providedis a cable brake as is conventional, incorporated in the traveler 54 orwhich is a brake on the right hand end piece 70 b. Further detail of thecable spool arrangement is shown in FIG. 3B with identical referencenumbers to that of FIG. 3A. Also shown are supports 82 a, 82 b forrespective end pieces 70 a and 70 b where the supports 82 a, 82 b areattached to the chassis 14 or housing 16 in to hold the cable spoolassembly.

FIG. 4 shows detail of props 36 a, 36 b with respective extensions 40 a,40 b and a common base 90 which is fixed within the housing. Otherarrangements for fixing the props are possible. Telescoping of thestruts 36 a, 36 b is accomplished by electric motors or hydraulic meanswith a suitable locking mechanism if needed to keep the struts extended.Typically, when the submersible 12 is moving through the pipe, thestruts are collapsed and are extended and locked when it is desired tofix the submersible into position in the conduit. The bottom surface ofthe submersible 12 or tracks or skids then would rest on the conduitfloor. The submersible 12 may have positive buoyancy, in which case itmight ride along the top or sides of the conduit. In any case, struts 36a, 36 b are used to fix the submersible into position. Hence, they arenot limited to a negative buoyancy submersible. To give an example ofscale, in one embodiment when fully extended each strut 36 a, 36 b isapproximately six feet (2 meters) long. This would accommodate asubmersible for use in a conduit which is approximately 8 to 10 feet indiameter; that is, 2½ to 3 meters. Of course, none of these dimensionsare limiting.

Additionally provided associated with submersible 12 is a cable severingmechanism. This is not shown in the earlier figures for simplicity, butis in FIG. 5A, which is a partial cut away view showing structuressimilar to those of FIG. 1A, including the horizontal members 74 onwhich the cable traveler rides, and a portion of the cable 30 passingthrough the severing mechanism (guillotine) 96. In this case thesevering mechanism 96 includes framework 100 attached to housing 16.Framework 100 carries vertically traveling blade 102, which is actuatedby member 106, coupled to an actuator 108 moving vertically. FIG. 5Bshows additional detail of the severing mechanism 96 identical to thatof FIG. 5A, also showing the horizontal support 112 which allows member106 to pivot. Actuator 108 rides in a hydraulic or other type ofactuating cylinder 118 horizontal member 112 pivots within pivot housing114. Of course, these details of the severing mechanism are merelyillustrative. Cable 30 passes through port 110 in housing 100 with theblade 102 passing down into the port 110 to sever cable 30 upon command.

It is understood that the submersible 12 typically carries onboardintelligence, including, for instance, a microcontroller and/ormicroprocessor, which conventionally actuates various of its mechanisms.Also submersible 12 may be controlled through remote signals which areprocessed by the microprocessor/microcontroller. As explained above, inevent of failure of the cable the submersible operates autonomously(under its own control), at least on a limited basis. The cable severingmechanism as described above is intended to be operative when the cableis fouled and cannot otherwise be retrieved or freed and it is desiredto allow the submersible 12 to continue its movement autonomouslythrough the conduit for recovery.

This disclosure is illustrative, not limiting; further embodiments andmodifications will be apparent to one skilled in the art in light ofthis disclosure and are intended to fall within the scope of theappended claims.

1. An unmanned submersible vehicle, comprising: a submersible housing; arechargeable battery system located in the housing; a turbine associatedwith the housing, whereby the turbine is driven by a flow of water pastthe housing; and a generator coupled to the turbine, wherein thegenerator is electrically coupled to recharge the battery.
 2. Thevehicle of claim 1, wherein the turbine includes an impeller external tothe housing.
 3. The vehicle of claim 1, wherein the turbine is at leastpartly internal to the housing
 4. The vehicle of claim 1, furthercomprising: an axle with wheels or tracks mounted external to thehousing; and a motor in the housing and coupled to drive the wheels ortracks; wherein the motor is electrically coupled to the battery.
 5. Thevehicle of claim 1, further comprising a member extensible outward fromthe housing thereby to bear against a surface to inhibit movement of thevehicle relative to the surface.
 6. The vehicle of claim 5, wherein themember terminates in a curved portion.
 7. An unmanned submersiblevehicle, adapted to receive and/or transmit signals along a cablecoupled to a base, the vehicle comprising: a submersible housing; acable spool mounted to the housing; and a spool control coupled to thecable spool, whereby the cable in operation unspools from the cablespool as the vehicle moves away from the base.
 8. The vehicle of claim7, wherein the spool control includes a cable brake.
 9. The vehicle ofclaim 7, wherein the cable spool is mounted external to the housing. 10.The vehicle of claim 7, wherein the cable spool is mounted internal tothe housing and the cable passes from the cable spool through a portdefined in the housing.
 11. The vehicle of claim 7, wherein the spoolcontrol includes a motor coupled to rotate the spool.
 12. The vehicle ofclaim 7, further comprising a traveler mounted to the cable spool andmovable along the cable spool.
 13. The vehicle of claim 7, furthercomprising a length of negatively buoyant cable adapted to be spooled onthe cable spool.
 14. The vehicle of claim 7, wherein the cable includesan optical fiber.
 15. The vehicle of claim 7, further comprising asevering mechanism mounted adjacent the cable and adapted to sever thecable.
 16. The vehicle of claim 15, further comprising a controller inthe housing, wherein in normal operation the controller is incommunication with the base location via the cable, and upon a severingof the cable, the controller autonomously controls operation of thevehicle.
 17. The vehicle of claim 16, wherein the controller isoperatively coupled to the severing mechanism, thereby to sever thecable upon determination by the controller of predetermined conditions.